1. Graduate School of Frontier Biosciences, Osaka University, Suita 565-0871, Japan
2. Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan
3. Electron Microscope Laboratory, Keio University School of Medicine, Shinjuku-ku, Tokyo, 160-8582, Japan
4. Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, Kobe 651-2492, Japan